Phosphorus-sulfur compounds



Paw

United States PHOSPHORUS-SULFUR COI'VIPOUNDS Gail H. Birum, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application February 11, 1954 Serial No. 409,774

Claims. (Cl. 167-22) The invention relates to organic compounds containing phosphorus and sulfur and deals more specifically with compounds of the thiophosphite series.

The invention provides as new compounds thiophosphites having the general formula:

Rs ,Pc1,

8- (p-chlorophenyl) dichlorothiophosphite, Bis [S- (p-chlorophenyl) chlorodithiophosphite, and Tris [S- (p-chlorophenyl) ]trithiophosphite I have found that the present organic compounds may preferably be prepared by contacting elemental phosphorus with a sulfenyl chloride, RSCl, in which R is selected from the class consisting of alkyl radicals having from one to four carbon atoms, aryl radicals, and heterocyclic radicals. Sulfenyl chlorides which may be employed include aliphatic sulfenyl chlorides, such as monochloromethanesulfenyl chloride, dichloromethanesulfenyl chloride, trichloromethanesulfenyl chloride, 2-chloroethanesulfenyl chloride and tert.-butanesulfenyl chloride. Aromatic sulfenyl chlorides which may be employed in the same relationship include benzenesulfenyl chloride, p-chlorobenzene sulfenyl chloride and other chloroand/or intro-substituted compounds. The phenyl group may also be substituted with conventional radicals such as nitrile, sulfonyl or acyl groups, such as acetyl, for example. In addition to the phenyl radical the naphthyl derivatives may similarly be employed. The present reaction may also be carried out employing heterocyclic sulfenyl chlorides, such as Z-benzothiazolesulfenyl chloride, Z-thiazolesulfenyl chloride and other thiazyl derivatives. In addition to the chloride derivatives, the corresponding bromides may similarly be employed.

The source of phosphorus in preferred method of the present invention is elemental phosphorus. The preparation of the compounds may be carried out by mixing the elemental phosphorus with the sulfenyl chloride. The reaction occurs to a considerable extent at room temperature, but is accelerated at higher temperatures, such as from to 200 C., a preferred range being from 50 C. to 125 C. If desired, a solvent such as xylene or benzene may also be employed. Distillation or crystallization is a preferred method of separating the final reaction products from the reaction mixture.

The present thiophosphite compounds are well-defined materials which are advantageously employed for a number of industrial purposes and are particularly valuable as chemical intermediates in the preparation of compounds having the thiophosphite radicals as subatent G "ice stituents, particularly in view of the possibility of providing active chlorine radicals to enable further reactions to be conducted with the products of the present invention. The compounds of the present invention are also useful as insecticides and as herbicides for the selective elimination of undesirable weeds. The said compounds are also of utility as lubricant additives, for example, in the preparation of gear lubricants by the addition of the present compounds with heavier hydrocarbon fractions. 1

The present invention is further illustrated but not limited by the following examples:

Example 1 Yellow phosphorus (5.3 g.) is mixed with 200 ml. of toluene in a flask equipped with a stirrer, thermometer, condenser, a Dean and Stark trap, a nitrogen inlet tube and a dropping funnel. The nitrogen stream is introduced into the reactor and the mixture warmed at reflux temperature until the toluene distillate is clear and the phosphorus dissolved. p-Chlorobenzenesulfenyl chloride (46 g.) is then added by dropwise addition over a period of about one-half hour with the temperature maintained at about 5860 C. during the exothermic reaction. The solution is found to be rapidly decolorized during the exothermic reaction period. A yellow solid separates during the course of the reaction but is found to dissolve to give a yellow solution at C. In order to carry the reaction to completion 20.7 g. of additional p-chlorobenzenesulfenyl chloride is then added. The reaction vesset is cooled and the residual solid removed and purified by recrystallization from hexane to give the following thiophosphites:

S- (p-chlorophenyl) dichlorothiophosphite, B1s[S-(p-chlorophenyl)] chlorodithiophosphite, and Tris [S-(p-chlorophenyl) trithiophosphite It has been found that the use of elemental phosphorus is particularly advantageous in directing the reaction towards the production of thiophosphites.

Example 2 Phosphorus sesquisulfide (55 g.) and trichloromethanesulfenyl chloride (372 g.) were placed in a flask and warmed to about 80 C. At this temperature the mixture was entirely liquid. The reaction mixture was then cooled to about 50 C., at which temperature a solid began to separate. The temperature was then raised to 120 C. At the end of an hour the dark red liquid product was distilled to obtain three major fractions (A), (B) and (C).

Compound C, when subjected to insecticidal testing against tribolium showed kill at 1% concentration and also displayed moderate activity against the 2- spotted mite at 0.2% concentration. This compound also showed marked herbicidal activity.

When subjected to microbiological testing against Micro-cocoa: pyogeucs var. (nu-ens compound C was are proportions of l f 111.5 respectively.

, cold plate and allowed to harden.

followingtesting procedures were used.

to inhibit growth at 1: 10,000 concentration, and when employed against Salmonella typhosa, it inhibited aratioii into individual components was also tested for insecticidal and microbiologicalactivity, It was found i1% concentration. In bactericidal tests, inhibition of growth was obtained at 1:1,000 against Micrococcur yogenes var. am-ens and Salmonella typhosa, and at l:10,000 againstlAspergillus niger The mixtures of (A),

.(B) and (C) are effective in all proportions of the three components; the specific mixture. employed above had .The compounds .of the'prment invention have been found to possess activity as biological toxicants. The compound bis(S-trichloromethyl) chlorotrithiophosphate was tested against Aspergillus niger' using the following testing procedure; a i

Preliminaryr -Trommels malt agar was poured into a Petri' plate and allowed to harden. Ajcircular section was cut from the'center and into this cup was placed 0.1 gram of the test compound. The plate was then sprayed with a fresh aqueous spore suspension of Aspergillus niger and incubated at a temperature of 28 C. for five days. Inspection of the incubated plate at the end of that time showed no growth of Aspergillus niger within a mm.

zone. h

' Sec0ndary.--To 100 cc. of hot Trommels malt'agar was added 0.1 gram rof the-test compound. The agar Was then whipped into an emulsion and poured into a I 50 cc. of hot agar was added to 50 cc. of the above toxic agar to give acompound concentration 'of,0.05 percent. To cc. of the remaining toxic agar was added 90 cc. of agar to give a concentration of 0.005 percent. Petri dishes were filled from each of the two mixtures, i. e., that having a concentration of 0.05 percent and that having an 0.005

' and 0.005 percent concentration the growth of Aspergillus niger was completely inhibited.

In tests made on the spores of the fungus Micrococcus pyogenes Vaf.dlll2ZlS aconcentration of 1210,000 was found -to inhibit growth. When employed against Salmonella typhosa inhibitionpfgrowth was found to occur at 1:l0,000 concentration."

This testshows the insecticidal activity of compositions including .Sdrichloromethyl dichlorothiophosphate. The

l. Contact drop application.To fifth instar milkweed bugs there waslapplied a measured'drop of the crude mixture of (A), (B) and (C) above at 1.0 percent concentration in acetone on the dorsal part of the thorax. Application was by means of a micrometer device actuating the plunger of ahypodermic needle.

2. Residue t'est.Petri dishes were] sprayed with acetone solutions of the compound mixture at the concenwith the, 2-s'potted mite were sprayed with an atomizer 2 on both leaf surfaces at indicated concentrations of the compound mixture in .a cyclohexanone-water emulsion. The plants are thenheld for 7 days for observation of kill of .mites and their eggs. i

4.;Contactof residue on'p lants.--Free bean plants were sprayed with a cyclohexane-water emulsion of the, compound mixture atthe indicated concentration, the j spray on the plants was allowed to become thoroughly ,that a 100% kill against' milkweed .bug was obtained at dry, and mites were transferred to plants supporting the dried residue. At the end of 7 days, observation was, 7

made of kill of mites. r. a

The present compounds are generally applied for insecticidal use in the form of sprays or aerosols. The spray may be prepared by dissolving the compounds in the usual crganic'sol fents, 'e. g., acetone, hexane, benzene or carbon tetrachloride or'by incorporating them into aqueous' emulsions. The compounds may also be dissolved in liquefied gases such as the fluoro'chloroethanes or methyl-chloride and applied from aerosol bombs made from the solutions.

instead of employingliquids as carriers and diluents,

insecticidal dusts comprising the present compounds may more gradual. .It was also observed that the reaction proceeded with a slow evolution of acidic gases.

Example 4 phenyl) dichlorodithiophosphate and bis[S- (para-chloro-.

phenyl)] chlorotrithiophosphate.

Example 5 A reaction similar to that of Example 2 was conducted employing phosphorus sesquisulfide with ortho-nitrobenzenesulfenyl chloride. The products obtained in this case were S-(ortho-nitrophenyl) dichlorothiophosphite, S-

(ortho-nitrophenyl) dichlorodithiophosphate and bis[S (ortho-nitrophenyD] chlorotrithiophosphate. Whatis claimedis: V v i i 1. The method of preparing compounds havi g the formula in which R is selected from the class consisting of alkyl '1 radicals having from one to four carbon atoms, aryl radicals and heterocyclic radicals, x is a number from one to three, inclusive, y is a number from zero to two, inclusive and x plus y equals three, which'comprises reacting elemental phosphorus with a sulfenyl chloride,

RSCl, in which R' is selected from the class consisting of S-trichloromethyl dichlorothiophosphite S-trichloromethyl dichlorodithiophosphate, and

Bis(S-tricloromethyl) chlorotrithiophosphate 4. The method of destroying insects which comprises exposing said insects to a toxic quantity of an insecticidal composition comprising an inert carrier and as the active The reaction of phosphorussesquisulfiedwith para-.

5 ingredient in a quantity which is toxic to insects, a mixequals three, which comprises reacting elemental phosture of: phorus with a sulfenyl chloride, RSCI, in which R is an Strichlommethsll dichlomthiophosphite alkyl radical having from one to four carbon atoms.

s trichloromethyl dichlorodithiophosphate, and

Bis(S-trichloromethyl) chlorotrithiophosphate 0 References Cted the file fth1s Patent 5. The method of preparing compounds having the UNITED STATES PATENTS Emma 1 2,188,943 Evers Feb. 6, 1940 (RSEPC 2,321,307 Nuheska et al. June 8, 1943 in which R is an alkyl radical having from one to four 1 2,542,370 Stevens et al. Feb. 20, 1951 carbon atoms, at is a number from one to three, inclusive, 2,679,508 Gysin May 25, 1954 y is a number from zero to two, inclusive, and x plusy 2,682,554 Crouch et a1 June 29, 1954 

1. THE METHOD OF PREPARING COMPOUNDS HAVING THE FORMULA: 